Final answer:
The statement that natural draft cooling towers are often hyperboloid structures is true. This shape enhances the efficiency of the cooling by facilitating natural upward airflow, which is particularly useful in nuclear and coal-fired power plants for condensing steam in their secondary cooling circuits.
Step-by-step explanation:
The statement that natural draft cooling towers are often shaped as a hyperboloid of revolution is true. These cooling towers are designed with a hyperbolic shape because it naturally facilitates the draft of air through the tower, enhancing the cooling process without the need for mechanical fans. The hyperbolic structure is wider at the base and narrower at the throat before flaring out again at the top, allowing hot, moist air to rise more efficiently due to the increase in airflow speed as it ascends, which aids in the creation of a natural draft to cool the water more effectively.
A nuclear power station and a coal-fired power station utilize this type of cooling tower because they require significant amounts of cooling for their operations. In a nuclear power plant, water is used to absorb heat from the reactor's core and is then transported to a cooling tower where it releases heat into the atmosphere before being recycled back into the system. The iconic large hyperbolic cooling towers often seen at power plants are instrumental in the process of condensing steam from the secondary cooling circuit.